Four beautiful moons, big mysteries, and few answers any time soon

During the last couple of nights the moon and Jupiter have appeared close to one another in the sky. This conjunction hasn’t been quite as spectacular as last month’s, but it’s still been pretty good as the photos below attest.

In the first image Greg Gibbs of Capturing the Night caught a great photo of the moon, Jupiter and an airplane. He then took an overexposed image to bring up three of the Galilean Moons of (from left to right) Io, Callisto and Europa. Ganymede had already been occulted by The Moon.

Fly me to the moon. (Greg Gibbs)

Be sure to click the image to enlarge it for the full effect.

The second photo showing off the Jupiter-Moon conjunction comes from David Finlay, and Australian photographer. This photo has been slightly enhanced, but it’s definitely real.

Jupiter and five moons. (David Finlay)

The most spectacular feature of this photo, I believe, is the clarity of Jupiter’s four major moons.

These four moons were discovered just over 400 years ago by Galileo Galilei after he improved his rudimentary telescope by increasing its magnifying capability to 20x. The discovery helped cement the role of telescope in astronomy — yes, at the time there was a debate about whether objects were visible in the sky beyond what the naked eye could see.

More importantly they provided concrete observational evidence to support the Copernican theory of the solar system, which held that the planets revolved around the Sun, rather than around the Earth as Ptolemy (and the Catholic Church) taught. Copernicus, by the way, was born 540 years ago today.

Galileo’s writings on the moons eventually led to his indefinite imprisonment by the Catholic Church in 1633. Hey it was Italy. Today you can get a similar rap in that country for failing to accurately predict an earthquake.

Anyway, these moons are among the most interesting objects in the solar system. One of them, Europa, is right at the top of my list to better understand. The moon has more water on it than the Earth does.

A comparison of water on Europa, left, and the Earth. (NASA)

Slightly smaller than our own moon, Europa has an oxygen atmosphere and a vast water ocean is believed to exist beneath its surface of ice due to internal heating. Europe is planning to launch a probe to explore three of the Galilean moons, including Europa, in 2022. The United States also has plans for a Europa clipper, but the $2 billion mission has no funding.

We’d begin to get data from the European probe in 2033 or so. That’s a very long time to wait for answers, alas.